Rails 5 essentials Shayan sobhanian

Upgrade to PostgreSQL 9.1 or Later

If you are using PostgreSQL as the database for your application, you must ensure that you are using PostgreSQL version 9.1 or higher. Previous versions are past their end-of-life date and support for them has been dropped from Rails 5.

Devise Gem

If your application makes use of the popular Devise gem for authentication, you need to change your Gemfile to use the most up-to-date commit from Devise’s page on the GitHub repository. At the time of writing, there is no official versioned release of Devise that is compatible with Rails 5; but the required changes have been committed to GitHub.

To do this, edit your Gemfile and change the entry for Devise as follows:

gem 'devise', git: 'git@github.com:plataformatec/devise.git'

You must then perform this:

$ bundle update devise

If you attempt to use an older version of Devise, you encounter the following error:

uninitialized constant ActionController::RackDelegation

Devise is a very popular gem, so this is a common problem to encounter when updating an app to Rails 5.

Callback Chain Changes

Rails 5 has slightly changed the behavior of callback chains .

In Rails 5, the preferred method to halt a callback chain is to explicitly call throw(:abort); whereas in previous versions of Rails, you could simply return false from a callback method.

When you upgrade an old application to Rails 5, the application still performs as expected, but you receive deprecation warnings. Once you have brought your application up to date, you can fully enable the new behavior and remove the deprecation warnings by adding an initializer file containing this line:

ActiveSupport.halt_callback_chains_on_return_false = false

New applications created with the Rails 5 application generator already include this config statement. Shayan sobhanian

This change is discussed in more detail in Chapter 2.

Running Tests

You should now be ready to run your test suite and start to pick off any necessary gems that require updating, one by one.

Remember, with Rails 5, you run your tests with the rails command rather than rake:

$ rails test

You will almost certainly find some deprecation warnings and some incompatible gems. Check the support pages for the gems as most will have been updated to work with Rails 5.

Chapter 2 details most of the changes and additions to the Rails API to help you understand how to update your application.